In order to detect cyanide compounds (CN compounds) in aqueous solutions, it is known from the prior art (DE102006026044A1) to first expel the CN compounds from the liquid phase into a gas phase and then to deduce the concentration of the CN compounds in the aqueous solution by using a gas sensor or gas analyzer to detect the expelled CN compounds, for example HCN. In order to expel the CN compounds, DE102006026044A1 proposes acting on the aqueous solution with a carrier gas. It also proposes using gas access determining equipment to detect the quantity of gas to be measured in order to thus achieve a precise measurement. Such equipment, however, is complex in design and results in a comparatively temperamental process. In addition, devices of this kind require a comparatively complex reactor with a temperature control device in order to ensure a controlled expulsion of the CN compounds and thus reproducible measurement results. Such reactors, however, do not permit rapid reaction to toxic solutions such as aqueous solutions with elevated concentrations of CN compounds; as a result of this, the method can in fact be used for verifying the concentration of CN compounds, but not for controlling a very rapid reaction chain.
In addition, it is known (DD 275 154 A3) to introduce a membrane module into an aqueous solution, with a carrier gas flowing through it, which is insulated in relation to the aqueous solution. Hydrocyanic acid can enter through the membrane module and, carried along by the carrier gas, can be subjected to a joint analysis. The above-cited reference also proposes taking into account the temperature of the aqueous solution for a measurement correction. A membrane module, however, is fairly susceptible to contamination so that it is not possible to guarantee a stable method and stable device. In addition, a general measurement of the temperature of an aqueous solution cannot enable achievement of a precise method.
The object of the invention, therefore, is to embody a method of the type described at the beginning so that it is possible not only to ensure a sufficiently precise determination of the concentration of CN compounds in an aqueous solution, but also to provide a continuous method. In addition, the method should be fast-reacting.